diff options
| -rw-r--r-- | mm/memcontrol.c | 57 |
1 files changed, 50 insertions, 7 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index b9afa060b8d6..9a62ac3ea881 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -346,6 +346,7 @@ struct mem_cgroup { /* internal only representation about the status of kmem accounting. */ enum { KMEM_ACCOUNTED_ACTIVE = 0, /* accounted by this cgroup itself */ + KMEM_ACCOUNTED_DEAD, /* dead memcg with pending kmem charges */ }; #define KMEM_ACCOUNTED_MASK (1 << KMEM_ACCOUNTED_ACTIVE) @@ -355,6 +356,23 @@ static inline void memcg_kmem_set_active(struct mem_cgroup *memcg) { set_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags); } + +static bool memcg_kmem_is_active(struct mem_cgroup *memcg) +{ + return test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags); +} + +static void memcg_kmem_mark_dead(struct mem_cgroup *memcg) +{ + if (test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags)) + set_bit(KMEM_ACCOUNTED_DEAD, &memcg->kmem_account_flags); +} + +static bool memcg_kmem_test_and_clear_dead(struct mem_cgroup *memcg) +{ + return test_and_clear_bit(KMEM_ACCOUNTED_DEAD, + &memcg->kmem_account_flags); +} #endif /* Stuffs for move charges at task migration. */ @@ -2722,10 +2740,16 @@ static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size) static void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size) { - res_counter_uncharge(&memcg->kmem, size); res_counter_uncharge(&memcg->res, size); if (do_swap_account) res_counter_uncharge(&memcg->memsw, size); + + /* Not down to 0 */ + if (res_counter_uncharge(&memcg->kmem, size)) + return; + + if (memcg_kmem_test_and_clear_dead(memcg)) + mem_cgroup_put(memcg); } /* @@ -2764,13 +2788,9 @@ __memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **_memcg, int order) return true; } - mem_cgroup_get(memcg); - ret = memcg_charge_kmem(memcg, gfp, PAGE_SIZE << order); if (!ret) *_memcg = memcg; - else - mem_cgroup_put(memcg); css_put(&memcg->css); return (ret == 0); @@ -2786,7 +2806,6 @@ void __memcg_kmem_commit_charge(struct page *page, struct mem_cgroup *memcg, /* The page allocation failed. Revert */ if (!page) { memcg_uncharge_kmem(memcg, PAGE_SIZE << order); - mem_cgroup_put(memcg); return; } @@ -2827,7 +2846,6 @@ void __memcg_kmem_uncharge_pages(struct page *page, int order) VM_BUG_ON(mem_cgroup_is_root(memcg)); memcg_uncharge_kmem(memcg, PAGE_SIZE << order); - mem_cgroup_put(memcg); } #endif /* CONFIG_MEMCG_KMEM */ @@ -4217,6 +4235,13 @@ static int memcg_update_kmem_limit(struct cgroup *cont, u64 val) VM_BUG_ON(ret); memcg_kmem_set_active(memcg); + /* + * kmem charges can outlive the cgroup. In the case of slab + * pages, for instance, a page contain objects from various + * processes, so it is unfeasible to migrate them away. We + * need to reference count the memcg because of that. + */ + mem_cgroup_get(memcg); } else ret = res_counter_set_limit(&memcg->kmem, val); out: @@ -4232,6 +4257,10 @@ static void memcg_propagate_kmem(struct mem_cgroup *memcg) if (!parent) return; memcg->kmem_account_flags = parent->kmem_account_flags; +#ifdef CONFIG_MEMCG_KMEM + if (memcg_kmem_is_active(memcg)) + mem_cgroup_get(memcg); +#endif } /* @@ -4920,6 +4949,20 @@ static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss) static void kmem_cgroup_destroy(struct mem_cgroup *memcg) { mem_cgroup_sockets_destroy(memcg); + + memcg_kmem_mark_dead(memcg); + + if (res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0) + return; + + /* + * Charges already down to 0, undo mem_cgroup_get() done in the charge + * path here, being careful not to race with memcg_uncharge_kmem: it is + * possible that the charges went down to 0 between mark_dead and the + * res_counter read, so in that case, we don't need the put + */ + if (memcg_kmem_test_and_clear_dead(memcg)) + mem_cgroup_put(memcg); } #else static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss) |